Heat exchange apparatus



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Jan. 10, 1933. G. c. BERRY I 1,894,026

`HEAT EXCHANGE APPARATUS Filed sept. 26. 1929 3 sheets-Sheet 1 Jan. 10, 1933. G. c, DERRY 1,894,026 HEAT EXCHANGE APPARATUS Filed Sept. 26. 1929 3 Sheets-Sheet 2 Wzes l 1g T am C. iv d N ha@ wfw' www/mw Jan. 10, 1933. G, C, BERRY 1,894,026

HEAT EXCHANGE ,APPARATUS Filed sept. 26. .1929 s sheets-sheet s Patented den., 10, 1933 @Mmmm C. @ERB/Y, 0F SHARUN, MASSACHUSETTS, SSGNOR T0 B. F. SWRTEVMTT www, @F HYDE PARK, lIASSACI-ITU'SETTS, A. CRPORATEON 0F MSSAGHUSETT@ HE'E EXCHANGE APLMTUS .application filed September 26, i929, Serial No. @$15,299.

The present invention relates to heat eX- change apparatus and more particularly to apparatus for extracting available heat from Waste gases in steam povver plants, oil stills and other apparatus.

A common type of heat transfer device used for obtaining heat from the Waste gases in a power plant is an economiser tor heating the i'eed Water for the boiler. ln modern plants, hovvever, Twherein steam at high pressure and temperature is generated in the boiler, the temperature of the feed Water entering the boiler is often so high that the :full available heat from the Waste gases is not extracted. This is particularly so in cases Where the feed Water is initially heated by so-called stage bleeding, so that it enters the economizer at temperatures as high as 300 or 350 and even higher. rlhe capacity tor heat transfer in any equipment is ldependent, among other factors, upon the heat head, that is, the dinerence in temperature between the iiue gases and the material to be heated. 'W ith high leed Water temperatures the heat head in an economiser is so tar diminished that the economiser has lost much of its usefulness in high pressure plants.

ln order to avoid the large stach loss brought about by the inability ot the econornizer to extract the available heat from the gases, air heaters are new commonly eniployed. These oii'er a higher heat head because of the :tact that the temperature of the air entering the air heater is considerably lovver than the temperature of the feed Water entering the economiser. 'lhe air heater is not always used Ito the exclusion Vof the econoinizer, a small economizer being usually provided 'for the purpose ol augmenting the temperature obtained in the stage heater. "When both an economiser and heater are used, the air heater Jlollorvs the economiser because et the higher heat head at the lovv temperature or inlet end. lrloivever, because ot the tact that the economiser absorbs a considerable part of heat from the iiue gases bef-ore the latter reach the air heater, there is a considerable loss of heat head at the outlet oi the air heater.' ln other Words, the

With these objects in viev-v the principal feature of the present invention consists ot a heat exchange apparatus having air and Water tubes Which are interspersed among one another, and adapted to be swept by the flue gases, both the air and Water tubes being so disposed as'to be subjected to the maximum available heat heada The apparatus in its preferred form eonsists of a single casing having a large number of air tubes and a lesser number oli ter tubes dispersed among the air tubes.

As a further feature, the invention centena plates the provision 'ot the vvater tubes with external extended surface whereby the heat absorbing capacity thereof is considerably increased over the heat absorbing capacity for plain tubes. .lhe total external surface of the water tubes ispreiterably equal to the amount oi suriace vvhicii would be provided by plain Water tubes or the saine diameter, and included in the same volume with :uninirnurn practicable spacing. rhus, the entenda ed surface vvater tubes permitted to be spaced at considerable distances troni one another, thereby leaving sufficient space lor insertion et plain air tubes. rthe number or air tubes for which space is provided among the Water tubes is ordinarily to maintain the proper temperature between the heat transferred to the vvater and he e transferred to the air.

ln the accompanying drawings l is an end vievv, partly in section, on line ll, 2, showing a preferred torni of heat archange apparatus embodying the features ot the the present invention g; illig. 2 is a sectional side view on line 2-2 of Fig. l; and Fig. 3 is a horizontal sectional View on line 3-3, Fig. 2.

The illustrated embodiment of the present invention comprises a casing having ends il and sides 6. Internally of the casing is provided a flue 8, bounded by the tube sheets l0 and l2. One end of the casing is formed with upper and lower air inlet and outlet chambers 14e and 16, separated by the horizontal partition or balile 18.

The apparatus is preferably constructed for counterflow between the flue gases and the air and 'Water to be heated. ln the preferred form of the ii sentieri the due gases from the boiler ascend uirough the 8, as indicated by the arrovf.7 the top and bottom, While tn f ano. water, entering at the top ot the a ,paratua discharged at the bottom.

Mounted in the tube sheets are a plurality of rows of air tubes which, as shown in i' l, are staggered. These tubes are expanded their ends to secure then/i in the 'tube sheets. The upper set of tubes, t is, those above the partition i8, convey (fr from the inlet chamber laf at one end e.- the reversing chamber 22 f t t where the partially downwardly and. baclr of tubesto the outlet cha; it is directed to the combustion furnace.

As shown in Fig. i, a number ,ot air tubes are omitted from alternate rows, in these spaces are located Water tubes These Water tubes convey feed Water from an inlet 26 at the top of the casing to an outlet 28 at the bottom. Eachwater tube is provided with extended heat absorbing surface in the form of flanges 30 whereby the external surface of each water tube is greatly increased. The Water tubes are all connected in series b return bends 32, and are staggered among t emselves and the air tubes.

In the illustrated embodiment of the present invention the Water tubes are provided with flanges of such size and spacing that the surface exposed to the hot gases is about seven times the surface of a plain tube of the same diameter. The use of extended surface on the Water tubes, therefore, adords Withonly one-seventh the number of tubes the same total heating surfaces that would be afforded by plain tubes.

Preferably the water tubes are of such number and so spaced that the total external heating surface of the Water tubes is approximately the same as the total amount of heating surface practicably available in an apparatus of the same size employing plain water tubes throughout. Sufiicient space is thus provided in the casing for the air tubes, which, since they require no bends or other connections, may be spaced in very close proximity to one another.

The air and Water tubes are kept clean and free from soot and dust by means of the soot blowers 34 which consist of steam pipes passing through the air inlet and outlet chambers and across the flue. These pipes are provided with the perforations 36 arranged to direct live steam at definite intervals onto the adjacent air and Water tubes to remove any accumulation of dust or soot.

The above described construction Wherein the air and Water tubes are located within the same casing and may be exposed to the same heat head provides a very compact and efticient apparatus. The use of extended surface on the Water tubes still further conserves space. Compactness is also secured by the close spacing of the air tubes both horizontally and vertically, and this, in conjunction with high gas velocity, results in increased rate of heat transfer and reduced accumulation of soot and dust.

While in the illustrated embodiment of the present invention the liuc gases are described as ascending While the Water and air have general descending path, it is to be understood that this is not an essential feature, but if desired, the directions of iiow may be changed although ordinarily the air and water will be opposite to that of the hot gases.

Nor is the present invention limited to lthe subjection of Water and gas to the entire heat head or to any definite proportion of air and Water heating surface. The conditions of the installation will determine the amount of heating surface required in the water tubes and similarly of the air tubes, and While preferably each series of tubes will be arranged so that both the air and Water will be subjected to the full heat head of the Hue gases, nevertheless the present invention contemplates a construction in which the Water tubes or air tubes may extend through only a portion of the heating chamber.

Having thus described the invention, what is claimed is:

1. Heat exchange apparatus for extracting heat from Waste gases comprising al Hue, air tubes and Water tubes in the flue adapted to be swept transversely by the hot gases, the Water tubes being interspersed among the air tubes and exposed to flue gases of the same temperature.

2. Heat exchange apparatus for extracting heat from Waste gases comprising a flue, air tubes and Water tubes in the flue adapted to be swept transversely by the hot gases, the Water tubes being regularly interspersed among the air tubes and being fewer in number than the air tubes and exposed to flue gases of the same temperature.

3. Heat exchange apparatus for extracting heat from Waste gases comprising a flue, air tubes and Water tubes in the flue, the Water tubes having extended surface and being nena,

widely spaced from each other, the air tubes being dispersed among the Water tubes and. exposed to the action of flue gases at the saine temperatures.

d. Heat exchange apparatus comprising a llue, air tubes and water tubes in the due, the water tubes having extended surface to :make the total heating surface of the water tubes approximately equal to the external surface ot the total number of lain tubes which could be practicably received in the casing, the water tubes being widely spaced apart, and a large nuinber of air tubes regularly dispersed in the spaces between thev water tubes.

5. Heat exchange apparatus tor extracting heat troni waste gases comprising a casing vhaving a llue tor the passage of hot gas and air chambers on opposite sides ozt the ilue, air tubes in the due connectin the air chambers, and water tubes in the ue exposed to dus gases and extending into the air chambers.

6. lleat exchange apparatus tor extracting heat 'troni waste gases comprising a casing having a due :For the passage ot hot gas and air chambers on opposite sides oiE the liuc, air tubes in the tine and connecting the air chambers, and water tubes in the rlue exposed to liuc gases and having return connecting bends in the air chambers.

'7. lrleat exchange apparatus tor extracting heat from waste gases comprising a casing having a due i-or the passage of hot gas and having an air inlet and an air outlet charnber in one side ot the casing and a reversing air chamber on the opposite side ot the casing, air tubes in the ue connecting inlet and outlet air chambers with the reversing air chamber, and water tubes in the ldue inter'- spersed among the air tubes, exposed to idue gases, and having their connections located in the air chambers.

8. Heat exchange apparatus comprising a casing having partitions therein to torni a tlue 'for the passage ot hot gas and air charnbers at ul`the sides ot the flue, air tubes niounted in the partitions and extending transversely through the flue and having open ends in the air chambers, and water tubes mounted in the partitions, said water tubes extending transversely through the duc with their ends extending into the air chambers, said tubes being provided within the ilue with extended external heating surface and having plain surface at their ends in theair chambers.,

9. l-leat exchange apparatus tor extracting "rorn waste gases comprising a vertical rlue, air tubes and water tubes in the due, the air tubes being arranged in horizontal rows and vertically staggered and the water tubes being interspersed among the air tubes and spaced apart on centers not less than the vertical spacing between the centers oie alternate rows oi air tubes.

l0. lleat exchange apparatus comprising a vertical due, air tubes and water tubes in the liuc, the air tubes being arranged in horizontal rows and vertically staggered, the water tubes being located in alternate rows of the air tubes, and spaced apart in said rows by a plurality ot air tubes.

l1. Heat exchange apparatus tor extracting heat from waste gases comprising a dus, air tubes and water tubes in the due the air tubes being arranged in ay plurality of groups each group providing a plurality oit parallel paths ot air dow in the sance direction across the due, and the water tubes being arranged in series to provide a single path ot dow.,

12. Heat exchange apparatus for extracting heat troni waste gases comprising a flue for the waste gases, air tubes extending across the llue transversely oi" the ilow ot gases and spaced close together, and Ywater tubes exposed to dus gases and interspersed among the air tubes.

i3. Heat exchange apparatus tor extracting heat trom waste gases comprising a. due tor the waste gases, air tubes exnding across the due and spaced close together, and water tubes having extended surface interspersed among the air tubes.

14. `Heat exchange apparatus comprising a flue tor the waste gases, air tubes extending across the due, water tubes having extended surface interspersed among the air tubes, the air and water tubes being spaced close together in staggered arrangement.

l5. l-leat exchange apparatus rrnprising a ilue for the waste gases, and air and water tubes extending across the due transversely ot the dow of gases and subjected to substantially the saine heat head.

le. itl-feat exchange apparatus comprising a i'due lor the waste gases, and air and water tubes extending across the idue transversely7 oit the dow of gases the water tubes being exposed to the lull heat head available in the waste gases i7. Heat exchange apparatus tor extracting heat from waste gases comprising a due having walls, air tubes extending across the due and having open ends expanded in the walls forming tight joints therewith, water;

tubes extending across the liuc and through said walls, and connections lor the water tubes outside the walls. n

18. Heat exchange apparatus for extracting heat trom waste gases comprising a due, air tubes and water tubes in the -due adapted to be swept by the hot gases, the water tubes being interspersed among the air tubes and the water and air tubes being closely spaced so as to cause high velocity ot dow of the due gases over the surfaces of the tubes.

19. lleat exchange apparatus comprising a due Jfor the waste gases, and air and water tubes extending across the flue transversely ot the ilow ot gases, all oit the air tubes having unobstructed interiors and being exposed to the full heat head available in the waste gases.

20. Heat exchange apparatus comprising flue for the Waste gases, and air and Water tubes extending across `the flue transversely of the ow of gases, the Water tubes being interspersed among and located exteriorly of the air uhes, and being .exposed to 1the Waste gases.

In testimony Whereonr l have signed my name to this specification.

GARDNER BERRY., 

